Let theta_j(z), j=2,3,4, be the Jacobi theta functions. For a positive integer r, let alpha_r:=theta_2(rz)^4/theta_3(rz)^4. Ramanujan discovered many algebraic relations between alpha_1 and alpha_r, called modular equations of degree r. In this talk, we present an approach that leads to many of Ramanujan's modular equations and beyond.